niti briefly - matt brock
TRANSCRIPT
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8/2/2019 NiTi Briefly - Matt Brock
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Introduction to NiTi The navy worked with NiTi alloy in the
1950s and 1960s
They were looking for a non-magnetic,
waterproof, and salt resistant material
Initial tests found NiTi to be superelastic
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NiTi particularly exhibits superelastic
behavior between 10oC125oC
Other alloys with superelastic properties are
the alloys of copper-zinc, copper-aluminum,
or titanium-niobium
Ideal temperature range in endodontics is
23oC to 36oC, the temperatures found in the
composition of 50% Ni and 50% Ti
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Orthodontics began using NiTi in the late
1970s
NiTi was also useful in wiring fractures in
orthopedics and oral surgery
Initial work proved NiTi resisted corrosionin the body and was extremely
biocompatible
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The First Use of NiTi in
Endodontic Hand Files Walia, Brantley, and Gerstein conducted the
first reported investigation of the NiTi alloy
in endodontics in 1988
Testing concluded that the NiTi had two to
three times the elastic flexibility and greaterresistance to torsion fractures
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By 1991 Quality Dental (Johnson City,
TN), developed a process for grinding NiTialloy files for NiTi Co. (Chattanooga, TN)
It was reported to be 500% more flexible
than conventional stainless steel and said to
be capable of withstanding 1000% morestress than conventional stainless steel
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University of South Carolina conducted astudy in 1992 with their pre-doctoral
students
Fewer cases of broken instruments,
perforations, and ledges occurred in thegroup using NiTi hand files
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University of Tennessee conducted a similarstudy in 1993 with their pre-doctoralstudents
Students using NiTi hand files had
significantly higher grades, instrumentedthe canals significantly faster, and hadoverall superior results
NiTi files seemed to work more efficientlyin a reaming motion rather than a filingmotion
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Table 1: This table illustrates the procedural errors
made by the students during their proficiency exam
with the two sets of files. (* Statistically significant)
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The First Use of NiTi in
Endodontic Rotary Files 1991 NiTi Co. had two rotary file designs to
make up their file line
These two file designs were developed
uniquely for continuous 360o rotation
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The first file design, U-File design, which
continues to be offered today as the Profile,
GT and LightSpeed, for sizes #15 through
#35
The second file design, the Sensor File, was
used in sizes #40-#60 and incorporated twosets of flutes having different helical angles
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Oregon Health Sciences Universitycompared four instrumentation techniques
1) Step-back preparation with K-files
2) Crown-down preparation with K-files
3) Sonic instrumentation with Shaper-
Sonic files
4) NiTiMatic preparation system with NiTi
rotary files
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Incidence of zipping, ledging, and elbow
formation was found to be the lowest with
the use of the NiTiMatic preparation system
with NiTi rotary files
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In 1993 the University of Tennesseeconducted a study comparing hand stainlesssteel, hand NiTi files, and the NiTiMaticpreparation system with NiTi rotary files
They found the rotary files to have achieved
the same shaping goals in about half thetime of the other two groups:
Rotary 173 s Hand stainless 328 s
Hand NiTi 351 s
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The NiTi rotary was found to have maintainedthe apical shape better, indicating fewer ziptype procedural errors
Amount of material removed at the workinglength:
Rotary 0.017 mm
Hand NiTi 0.023 mm
Hand stainless steel 0.139 mm
They also found the canal width of the innerwall to be closer to the original width and
more centered with the rotary group
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This illustrates the increase in canal width on the
inside of the curve at the point of curvature.